In this new post to the Stubbles blog Frank Kleine looks at the current state of annotations in the PHP language and applications.

Annotations are a really helpful feature in present-day development. An annotation is a special form of syntactic metadata that can be added to source code elements such as classes, methods, properties and parameters. They do not affect the program semantic directly, but can be used by tools and libraries to handle such annotated code in a certain way.

He notes that, as of right now, PHP doesn't naively support anything like this but that there are additional libraries that can be used to augment the standard PHP performance and use them (like a feature in PHPUnit with @assert and @test). He also go through several of the other libraries that make it possible including Addendum, FLOW3 and the XP-Framework.